Nick Hume's (Kevin Bacon) family is killed. Nick goes to Bones who sells him weapons to kill Billy's gang and Billy (Garrett Hedlund), Billy goes to his father and talks to him. His father criticized Billy, telling him that Joe was a better son than Billy ever was and that he shouldn't be hunting Nick down and that he's doing the wrong thing. Billy ignores him and kills him. Nick hunts down Billy's gang and kills them all, leaving only an injured Billy and Nick.
Billy apologizes for what he made Nick: a cold blooded killer. That's when Nick reveals a hidden Colt Python and asks Billy if he's ready to meet his maker. Billy sheds his final tear and Nick kills him (offscreen), we see Nick back in his house where he's watching a home video of his family and holding his bloody neck wound.
Detective Jessica Wallis (Aisha Tyler) tells Billy that his son moved and he's going to be alright. Nick smiles and looks back at the TV, finishing the home video. We're not sure of his fate as the film ends with him watching it.